This invention relates to an apparatus for changing artificial snow made by an artificial snow making apparatus to wet snow in order to conduct a snow settling test.
One conventional artificial snow making machine is disclosed, for example, in Japanese Patent Laid-Open No. 165,566/1986 and copending U.S. patent application Ser. No. 920,194, filed Oct. 17, 1986.
This prior art technique will be described with reference to FIG. 2 of the accompanying drawings. This apparatus comprises a vertical cooling tower 4, a snow collecting chamber 1 connected to the bottom of the cooling tower 4 and having an opening 3 in the ceiling thereof which is covered by the cooling tower 4, a first cooler 9 for cooling the air inside the cooling tower 4, an inner cylinder 12 disposed inside the cooling tower 4 in such a manner as to extend in the longitudinal direction of the cooling tower 4 and having an opening at the bottom thereof which is communicated with the opening 3 of the snow collecting chamber 1, a circulation pipe 13 communicating the top to the lower end of the inner cylinder 12, a variable speed blower 14 disposed at an intermediate portion of the circulation pipe 13, a humidifier 15 for supplying moisture into the inner cylinder 12 in the proximity of the lower end of the inner cylinder 12 and a snow seed feeder for supplying ice crystals into the inner cylinder in the proximity of the humidifier 15.
No apparatus is known in the art which changes the snowfall obtained by such an artificial snow making apparatus to wet snow.
A snow-covered power transmission line undergoes torsion when it collects snow in winter and is broken from time to time. This problem occurs particularly when the snow is wet snow.
A snow settling test can be conducted at a time of snowfall in winter but wet snow is not always obtained at the time of a snowfall. Even in Hokkaido which is the northernmost part of Japan, wet snowfall can be observed only once a winter or not at all. Therefore, a snow settling test is carried out by sieving the outdoor snow to granular snow, blowing a mist at a temperature of 0.degree. C. on the snow to wet it and causing the snow to impinge against a sample (e.g. a cable) inside an air channel to cause snow to settle thereon.
The problem here is that the properties of the snow created for such a snow settling test are entirely different from those of the natural wet snow, although the test uses the natural snow, and a reliable correlation cannot be established between them so that the snow settling test cannot be carried out accurately.
Accordingly, there is a strong demand for an apparatus for changing artificial snow to wet snow which can provide wet snow having properties almost equivalent to those of natural wet snow and which can immediately supply the wet snow thus obtained to a snow settling test.
The snow made by the conventional artificial snow making apparatus has the same crystal structure as that of the natural snow, but since the former is produced at a low temperature in the range of from about -5.degree. C. to -15.degree. C, its water content is low.
When formed high up in the sky, natural snow becomes the wet snow if the temperature on the ground is about 0.degree. C. Therefore, it is possible to change the artificial snow formed in the artificial snow making apparatus and falling thereinside to wet snow by rising the temperature.
If the temperature of the snowfall chamber (test chamber) disposed at a lower part of the artificial snow making apparatus is raised in order to obtain the wet snow, however, the air in the snowfall chamber rises due to convection and air having a negative temperature inside the inner cylinder 12 falls so that the ice crystals that have not yet grown to snow also fall and the snow cannot turn to the wet snow.
For this reason, too, there is a strong demand for the development of an apparatus for changing the artificial snow to wet snow in order to carry out a snow settling test.